Passive safety shield system for injection devices

ABSTRACT

A passive shield system for a syringe including a body, shield, spring and ring which provide an interlock of the shield in the retracted position prior to receipt of the syringe for bulk transportation and processing and wherein the user selects the timing of the release of the shield to its extended position following injection, but which assures shielding of the syringe needle following release of the syringe plunger.

This is a divisional of U.S. application Ser. No. 10/143,414, filed May10, 2002.

FIELD OF THE INVENTION

The present invention relates to a passive shield system for injectiondevices, including syringes, which prevents inadvertent or prematureactuation of the shield during normal bulk transportation, handling andprocessing and permits the user, such as a healthcare worker or patient,to select the timing of the actuation of the shield while assuringshielding of the needle or cannula without additional manualmanipulation.

BACKGROUND OF THE INVENTION

Injection devices including syringes are well known medical devices foradministering medicaments, drugs and vaccines to patients. As usedherein, the term “syringe” is intended to cover the various types ofinjection and medical delivery devices. They are also used for otherwell known purposes in the medical field. Prefilled syringes, forexample, are generally considered as those which are filled with aselected dosage of medicament, drug or vaccine by a pharmaceuticalmanufacturer for distribution to the end user. They are generallycomprised of a tubular barrel, which contains the medicament, drug orvaccine and a stopper is slidably received in the barrel. The distal endof the barrel typically includes a needle cannula affixed thereto or aconnector for a hypodermic needle, such as a Luer fitting. The openproximal end of the syringe barrel generally includes an integral radialflange and a stopper is inserted by the pharmaceutical manufacturerfollowing loading of the barrel with a suitable medicament, drug orvaccine. The plunger of a prefilled syringe generally includes astopper, which is moveable in the syringe barrel, a plunger rod, whichextends through the open proximal end of the barrel with a thumb pad istypically integrally formed on the proximal end of the rod. The syringebarrel is typically formed of glass, but may be formed of any suitablematerial including plastic and metal. The plunger and stopper assemblyallows the user to apply manual force to the plunger, driving thestopper through the barrel and causing the medicament, drug or vaccineto be delivered through the needle cannula to the patient during aninjection.

The use of any sharp-pointed piercing element entails the risk of anaccidental needle stick. To avoid accidental needle sticks, the priorart has proposed various types of safety shields for syringes includingprefilled syringes as described above. Such safety shields typicallyinclude a tubular shield or needle cover which is located in a retractedposition for injection and an extended position following injectionenclosing at least the end point of the needle cannula of the syringeand preventing accidental needle sticks. The tubular shield or needlecover of the syringe shield systems proposed by the prior art aretypically mounted on a body having a cavity for receipt of a syringe andthe syringe is inserted into the body by the pharmaceutical companyafter filling the syringe with a suitable medicament, drug or vaccine.Alternatively, the shield may be mounted directly on the barrel of thesyringe.

There are generally three types of safety shield systems for syringesproposed by the prior art. The first type may be characterized as manualshield systems. That is, the shield or needle cover is manuallymanipulated by the user to move the needle cover from the retractedposition, wherein the needle is exposed for injection or aspiration inthe case of reconstitution or vein test, to the extended position,wherein the needle is enclosed. Such manual shield systems typicallyinclude some means to prevent the shield from being inadvertently movedto the extended position and prevent the shield from retractingfollowing shielding of the syringe needle cannula, such as detents,interlocking ribs, threads, spiral grooves and the like. The principaldisadvantages of manual syringe shield systems are that there is nopositive assurance that the user will properly shield the needle cannulafollowing use or that the needle cover is properly locked in theshielded position. In addition, some designs can allow inadvertentactivation of the shield.

A second type of shield systems for syringes may be characterized asactive shield systems. Active shield systems will typically include anenergizer, such as a spring, which biases the shield or needle covertoward the extended position. Generally, the shield is initiallyretained in the retracted position by ribs, detents or the like andactuated by some action by the user. The principal advantage of activesyringe shield systems is that, upon activation by the user, the shieldor needle cover will move to enclose the needle cannula and lock theshield. Such active shield systems are generally activated by a button,movement of a component following injection or other release mechanism.That is, the user can generally activate the shield following injectionto avoid contact of the shield with the patient's skin prior todisposal. The principal problem with active shield systems for syringesis that again there is generally no positive assurance that the end userwill properly shield the needle cannula of the syringe. Further, theshield may be inadvertently or prematurely activated prior to use asdiscussed further below. The shield may also be inadvertently orprematurely activated particularly during bulk shipping and processing.

The third type of shield systems may be characterized as passive shieldsystems. Passive shield systems also include an energizer, such as aspring, biasing the shield or needle cover toward the extended positionas described above in regard to the active shield systems. However, theshield system is activated automatically generally upon completion ofthe injection. The primary disadvantages of the passive shield systemsproposed by the prior art are that the user cannot select the timing ofthe actuation of the shield system and the shield or needle cover may beinadvertently or prematurely activated prior to use or completion of thedelivery of the fluid in the syringe. That is, the shield can beactivated while the needle cannula remains in the patient or the shieldmay be prematurely activated, particularly during normal manufacturingand assembly procedures and shipping. Shield systems are generallymanufactured and assembled by the manufacturer of the shield system. Theshield systems are then transported in bulk to a pharmaceutical companyand must be handled using automatic feeding equipment, including feedbowls, etc., possibly resulting in inadvertent or premature activationof the shield.

The prior art also includes passive safety shield systems for syringes,wherein the shield system is actuated upon release of the plunger rodresulting in retraction of the syringe into the shield. However, in suchshield systems, the syringe is withdrawn into the shield as the plungerrod is released, requiring the user to maintain the plunger against theforce of the spring and requiring complete release of the plunger toshield the needle cannula of the syringe. In addition, the shield maycontact the patient's skin.

As described below, the passive shield system of this invention reducesthe likelihood of premature activation of the shield and permits the enduser to select the timing of the activation of the shield. That is, theuser can activate or authorize the activation of the shield afterremoving the needle cannula from the patient, thereby reducing the riskof hitting the patient's skin with the shield or needle cover. Further,the shield or needle cover moves axially relative to the syringe toenclose the needle cannula and lock the shield in the extended positionfollowing actuation, requiring only release of the plunger thumb pad.

SUMMARY OF THE INVENTION

As set forth above, the safety shield system of this invention ispassive, but avoids the problems associated with the prior art passiveshield systems. The shield system of this invention may be utilized withprefilled syringes of the type described above, but may also be usedwith other types of injection devices. Premature or inadvertentactuation of the shield system is minimized by an interlock system whichallows packing, transportation in bulk and high speed feeding systems inbowls, etc. Further, the needle cover or shield is moved to enclose theneedle cannula by release of the plunger, thereby giving the user theoption of releasing the needle cover only after complete delivery of thefluid in the syringe and removal of the needle cannula from the patient,while assuring shielding of the syringe needle cannula prior todisposal.

The disclosed embodiment of the passive shield system of this inventionincludes four components, namely a generally tubular body having an openproximal end for receipt of a syringe, a generally tubular shield orneedle cover telescopically supported by the body and extendable from aretracted position, wherein the syringe needle cannula is exposed, to anextended position enclosing the needle, a spring biasing the shieldtoward the extended position, and an annular or ring shaped member whichinterlocks with the body to prevent premature actuation of the shield orneedle cover and which actuates the shield upon release of the plungerfollowing complete delivery of the substance in the syringe. In thedisclosed embodiment of the shield system of this invention, the needlecover or shield is telescopically received within the body and moveableaxially to shield the needle cannula of the syringe as described. Thespring and the ring shaped member are received in the open proximal endof the body such that the spring is biased between the ring shapedmember and the shield. Prior to receipt of the syringe, the ring shapedmember serves as a locking member preventing premature actuation of theshield. The ring shaped member or locking member includes a leg whichforms a mechanical interlock with the body. In the disclosed embodiment,the ring shaped member includes two opposed axially extending legswhich, in the preferred embodiment, extend proximally, preferably beyondthe open end of the body, for actuation of the shield as describedbelow. In the disclosed embodiment, the legs include opposed V-shapedlocking surfaces which form a mechanical interlock with an opposedsurface of the body adjacent the open proximal end preventinginadvertent or premature actuation of the shield during bulk shippingand processing as described above. In one disclosed embodiment, theprojecting legs of the ring shaped locking member are partially enclosedor surrounded by walls which minimize inadvertent release of the shieldby the user. Upon loading of a syringe in the open proximal open end ofthe shield system, the syringe flange engages the proximal end of thering shaped member, driving the ring shaped member distally and the legsof the ring shaped member releasing the interlock between the ringshaped member or locking member and the body for actuation of the shieldas now described.

In the preferred embodiment of the shield system of this invention, thetubular needle cover or shield includes at least two fingers whichextend axially from the proximal end of the needle cover, each having aradial portion which is received on an opposed radial portion or ledgeof the generally tubular body and releasably supports the needle coveror shield on the body. The radial portions on the fingers areoperatively spaced relatively axially, such that the fingers functionindependently during actuation of the shield as described below.However, the radial surfaces or ledges on the body may alternatively bespaced axially and the radial portions of the fingers are then spacedaxially only if required. One of the fingers is angled or bowed towardthe radial support surface of the body, such that the angled or bowedfinger is initially supported on the body prior to actuation of theshield. In the disclosed embodiment, the shield includes four fingers,wherein two opposed pairs of fingers are angled or bowed toward theradial support surfaces of the body and the other pair of fingers extendgenerally axially or are bowed away from the body, providing balancedsupport for the shield.

Upon receipt of the syringe in the open proximal end of the shieldsystem, the interlock between the body and the ring shaped member isreleased and the ring shaped member is free to move axially in the bodyagainst the force of the spring. The annular or ring shaped memberincludes a first distal camming surface opposite the finger. In thedisclosed embodiment, the shield includes two pairs of fingers oppositethe outwardly angled or bowed fingers being referred to hereinafter asthe first pair of fingers. When the tubular shield or needle cover istelescopically received within the body, as described above, the firstpair of fingers bowed or angled outwardly and the radial portions arespaced distally from the radial portions of the fingers which extendgenerally axially or are angled inwardly, which are referred tohereinafter as the second pair of fingers. The first pair of fingerstherefore initially retains the shield in a first retracted position.The ring shaped member also includes a second camming or biasing surfaceor surfaces opposite the second pair of fingers of the needle cover.

The shield is thus actuated in stages, as follows. First, as theinjection is made, the thumb pad of the plunger assembly of the syringeengages the proximally extending legs of the ring shaped member, drivingthe ring shaped member distally in the body. The first camming surfacesof the ring shaped member opposite the first pair of fingers thenreleases the first pair of fingers and the shield moves axially to asecond retracted position because the second biasing or camming surfacesof the ring shaped member opposite the second pair of fingerssimultaneously biases the second pair of fingers radially outwardly toreceive the radial surfaces on the opposed radial surfaces or ledges ofthe body, releasably retaining the shield in a second retractedposition. In the preferred embodiment, the second retracted position isclose to or adjacent the first retracted position of the shield. Then,upon completion of the injection and release of the plunger by the user,the spring biases the ring shaped member proximally, releasing thesecond pair of fingers, and the shield is then driven distally to shieldthe needle as described. In the preferred embodiment, the body furtherincludes opposed detents adjacent the distal end of the body whichreceive a radial portion or annular rib of the shield adjacent itsproximal end which prevents retraction of the shield followingactuation. The shield system of this invention is thus passive in thesense that an additional action by the user is not required to activatethe shield. That is, the shield is automatically activated upon releaseof the plunger. However, the user can also select the timing of theactuation of the shield, for example, by releasing the plunger afterremoval of the needle cannula from the patient, thereby eliminatingengagement of the needle shield against the skin of the patient.Further, upon release of the syringe plunger by the user, the springdrives the shield from its second retracted position to its extendedposition, enclosing the syringe needle cannula, rather than retractingthe syringe into the shield as disclosed in the prior art. Anotheradvantage of the shield system of this invention is that it may be usedwith conventional syringes without requiring special plungers, thumbpads, etc. A further advantage is that the shield system of thisinvention may be designed for different sizes of syringes.

As set forth above, the syringe is received in the open proximal end ofthe shield system. In the disclosed embodiments, the syringe is retainedin the body by opposed abutment surfaces adjacent the open proximal endof the body which receive the flange of the syringe therebetween. In onedisclosed embodiment, the open proximal end of the body includesinwardly inclined camming surfaces which are engaged by the flange ofthe syringe. The camming surfaces bias the retainer elements to retainthe syringe flange between the opposed abutment surfaces. The proximalend of the body also includes lateral slots defining the opposed distalabutment surfaces. Finally, the proximal end of the body includes axialslots which receive the legs of the ring shaped or locking member.

In another preferred embodiment, the proximal end of the body isgenerally planar and the body includes generally hook-shaped retainerelements. The abutment surfaces which retain the syringe flange comprisethe generally planar open proximal end of the body and the overlyinghook-shaped elements. This embodiment includes two pair of spaced ribson opposed sides of the body which receive the legs of the lockingmember therebetween each having an inwardly facing proximal hook-shapedend portion which receives and retains the syringe flange and anoutwardly facing proximal hook-shaped end portion which receives thelocking portion of the ring shaped member. In this disclosed embodiment,the opposed sides of the proximal open end of the body also includesopposed abutment surfaces supported on posts extending from the planaropen end of the body which also receive the syringe flange. In thisembodiment, the syringe flange is substantially exposed permittingvisual inspection of the securement of the syringe in the body.

Other advantages and meritorious features of the shield system of thisinvention will be more fully understood from the following detaileddescription of the preferred embodiments, the appended claims and thedrawings, a brief description of which follows. As will be understood,the terms proximally and distally are used herein for descriptivepurposes only and the term proximally refers to the components orportions of a component closest to the hand of the user, such as ahealthcare worker or patient, and the term distally refers to thecomponent or a portion of a component furthest from the hand of theuser. Further, the preferred embodiments of the shield system forsyringes described below are intended to be exemplary only and do notlimit the invention except as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side perspective view of one embodiment of the shield systemof this invention prior to receipt of a syringe;

FIG. 2 is a side partially cross-sectioned perspective view of theshield system shown in FIG. 1;

FIG. 3 is a partial side view of FIG. 1 illustrating the interlockfeature of this invention with a partial view of a syringe shown inphantom;

FIG. 4 is a top view of FIG. 3 in the direction of view arrows 4-4;

FIG. 5 is an exploded view of the shield system shown in FIG. 1 with aconventional syringe prior to receipt of the syringe in the shieldsystem;

FIG. 6 is a partial side view of the proximal end of the shield systemwith a syringe received in the shield system;

FIG. 7 is an end cross-sectional view of FIG. 6 in the direction of viewarrows 7-7;

FIG. 8 is a perspective side view of the syringe and shield systemassembly during use of the syringe for an injection;

FIG. 9 is a side perspective view similar to FIG. 8 upon completion ofthe injection;

FIG. 10 is a side perspective view similar to FIGS. 8 and 9 followingcompletion of the injection and beginning of release of the plunger;

FIG. 11 is a side perspective view of the syringe and shield systemfollowing release of the plunger and extension of the needle cover orshield;

FIG. 12 is an exploded side perspective view of the components of theshield system illustrated in the prior figures;

FIG. 13 is a top view of the body of the shield system;

FIG. 14 is a top view of the tubular needle cover or shield;

FIG. 15 is a top view of the annular or ring shaped member;

FIG. 16A is a side partial cross-sectional view of the partiallyassembled components of FIGS. 13 to 15 in the direction of view arrowsX-X, also shown in FIG. 1;

FIG. 16B is a partial side cross-sectional view of the partiallyassembled components of FIGS. 13 to 15 in the direction of view arrowsY-Y, also shown in FIG. 1;

FIG. 17A is a partial side cross-sectional view of the assembledcomponents of FIGS. 13 to 15 in the direction of view arrows Z-Z, alsoshown in FIG. 1;

FIG. 17B is a partial cross-sectional view of the assembled componentsshown in FIG. 17A in the direction of view arrows X-X;

FIGS. 18A to 18C are partial cross-sectional views of the assembledcomponents of FIGS. 13 to 15 in the direction of view arrows Z-Z duringassembly of the syringe in the shield system;

FIGS. 19A to 19E are partial cross-sectional views of the syringe andshield assembly during injection and actuation of the shield, whereinthe left-hand portion is a partial cross-section through view arrows X-Xand the right-hand portion is a partial cross-section through viewarrows Y-Y;

FIG. 20 is a partial cross-sectional side view of the distal end portionof the body and the proximate end portion of the shield illustratinglocking of the shield in the extended position;

FIG. 21 is a top perspective view of an alternative embodiment of theshield system of this invention with a syringe assembled in the shieldsystem;

FIG. 22 is a top perspective view of the body of the alternativeembodiment of the shield system shown in FIG. 21;

FIG. 23 is a partial side view of the body of the shield system shown inFIG. 22;

FIG. 24 is a side cross-sectional view of FIG. 23 in the direction ofview arrows 24-24; and

FIG. 25 is a side partially cross-sectioned view of the shield systemillustrated in FIG. 21 prior to receipt of the syringe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As set forth above, the preferred embodiments of the shield system 20shown in FIGS. 1 and 2 includes four components comprising a generallytubular body 22, a generally tubular needle cover or shield 24, anannular or ring shaped member 26 and a spring 28 best shown in theexploded view of FIG. 12. The body 22 includes an open proximal end 30and an open distal end 32. The open proximal end 30 in the disclosedembodiment is generally rectangular or square having truncated corners34, inclined internal surfaces 36 at the open proximal end of the body,radial grooves 38 which receive the flange of the syringe describedbelow, axial grooves 40 which extend through the proximal end on opposedsides which receive the legs of the ring shaped member 26 describedbelow, and four radial surfaces or ledges 42 at the truncated corners 34shown in FIG. 12 which receive the radial portions of the fingers of theneedle guard or shield 24 as also described below. The open proximal end30 of the body 22 may also be elliptical, oval or even cylindrical, butis preferably not cylindrical. The outer edges of the proximal end ofthe body are hook-shaped having a distal ledge 43 which forms theinterlock with the legs of the ring shaped member 26 as discussed below.The body 22 further includes opposed finger flanges 44 adjacent the openproximal end 30, a tubular barrel portion 46 which, in the disclosedembodiment, has a cylindrical outer surface but other shapes may beselected. The tubular barrel portion 46 also includes detents 48 onopposed sides which prevent retraction of the needle cover once extendedas also discussed below.

The generally tubular needle cover or shield 24 includes an openproximal end 50 and an open distal end 52 as best shown in FIG. 12. Thetubular needle cover or shield 24 further includes an annular externalrib 54 adjacent the open proximal end 50 which is received by thedetents 48 on the distal end of the body preventing retraction of theshield as described below. The proximal end of the needle cover 24further includes two pairs of opposed fingers including a first pair offingers 56 and a second pair of fingers 58. As will be understood fromthe following description of the operation of the shield system 20 ofthis invention, the terms first and second pairs of fingers are fordescriptive purposes only and the shield system of this invention mayinclude only one finger of each of the pairs of fingers. Each of thepairs of fingers include a radial portion which are able to releasablyretain the needle cover 24 in a retracted position, wherein the radialportion 60 of the first pair of fingers 56 is spaced distally from theradial portion 64 of the second pair of fingers 58. The first pair offingers 56 also include an outwardly inclined camming surface 62 at theproximal ends of the fingers and the second pair of fingers 58 includean inwardly inclined camming surface 66 at their proximal ends.

The ring shaped member 26, also referred to as the locking memberbecause of its function in locking the shield system prior to receipt ofthe syringe 120 as described below, and shown in FIG. 5, includes anannular body portion 68 and a pair of opposed legs 70 which, in thedisclosed embodiment, are generally T-shaped including an inner baseportion 72 and an outer bridging portion 74. The bridging portions 74each include a V-shaped locking portion 76 which interlock with the bodyportion 22 as described below. The proximal open end of the ring shapedmember 26 includes an inclined or frusto-conical surface 78 which tapersinwardly from the proximal open end and an abutment surface 80 at thetermination of the inclined surface 78. The body portion 68 of the ringshaped member 26 also includes opposed axial ribs 82 each having anoutwardly inclined camming surface 84 at their distal end, best shown inFIG. 16B, and a pair of outwardly biasing surfaces 86 on opposed sidesof the body portion 68 having an arcuate distal end surface 88 as shownin FIG. 16A. The coil spring 28 is biased between the abutment surface80 of the ring shaped member 26 and the inner radial surface 90 betweenthe tubular shield and the first and second pairs of fingers 56 and 58,respectively, as best shown in FIGS. 16A and 16B. The generallycylindrical outer surface of the tubular shield 24 and the radial rib 54also include flat axially extending surfaces 94 and 96, respectively,which prevent rotation of the shield relative to the body 22 followingassembly.

As set forth above, one advantage of the shield system 20 of thisinvention is that it may be utilized to shield the needle cannula of aconventional syringe, such as a conventional prefilled syringe 120 shownin FIG. 5. As will be understood by those skilled in this art, aconventional prefilled syringe for example generally includes a tubularbarrel 122 having an open proximal end 124, a radial finger flange 126adjacent the open proximal end 124, generally integral with the barrel122, a needle cannula 128 at the distal end of the barrel 122 and aplunger assembly comprising a stopper 130 moveable within the barrel122, a plunger rod 132 affixed to the stopper and a thumb pad 134 at theproximal end of the plunger 132, generally formed integral with the rod132. The needle cannula 128 is generally covered with a needle sheath orcap 136. The barrel 122 may be glass, plastic or metal as set forthabove. The stopper 130 is typically formed of an elastomeric material,such as rubber or synthetic rubber, but may also be formed of plastic.The plunger 132 is typically formed of plastic. However, as set forthabove, the shield system 20 of this invention may be utilized with anytype of injection device and the shield system of this invention is notlimited to this type of syringe.

The shield system 20 of this invention may first be assembled by themanufacturer of the shield system prior to receipt of the syringe. Theshield system is assembled by inserting the needle cover 24 in the body22. In the disclosed embodiment, the needle cover or shield 24 istelescopically received in the open proximal end 30 of the body 22,wherein the radial portion 60 of the first pair of fingers 56 isreceived on the radial inner surfaces 42 of the body as best shown inFIG. 16B. Thus, the radial portion 60 of the first pair of fingers 56limits axial movement of the tubular shield 24 into the generallytubular body 46. The spring 28 is then inserted into the open proximalend 30 of the body where it is received against the radial surface 90 ofthe first and second pair of fingers 56 and 58 as shown in FIGS. 16A and16B. Next, the ring shaped member or locking member 26 is received inthe open proximal end 30 of the body, wherein the proximal end of thespring 28 is received against the abutment surface 80 and the spring 28is thus compressed between the abutment surface 80 of the ring shapedmember 26 and the opposed radial surface 90 as shown in FIGS. 16A and16B. As shown by comparing FIGS. 16A and 16B, the first pair of fingers56 are angled outwardly or toward the body 22, such that the radialportion 60 is received on the opposed internal radial surface 42 in thenormal position. The second pair of fingers 58 extend generally axiallyfrom the radial surface 90 or as shown in the disclosed embodiment, thesecond pair of fingers taper slightly inwardly such that the radialportion 64 of the second pair of fingers 58 will not be received on theopposed radial inner surface 42 of the body unless the fingers arebiased outwardly as described below.

The ring shaped member 26 is further compressed against the coil spring28 until the V-shaped locking portions 76 are received beneath theabutment or hook-shaped outer edge 43 of the body interlocking theshield system as described above. It should also be noted that the baseportion 72 of the leg 70 are slidably received in the axial slots 40 ofthe body as best shown in FIGS. 1 and 2. The inwardly inclined surfacesof the V-shaped locking portion 76 resiliently bias the legs 70outwardly to receive the transverse surface beneath the locking surface43 of the body. When the locking or ring shaped member 26 is interlockedwith the body as shown in FIGS. 1 and 2, the shield system cannot beinadvertently or prematurely actuated as described above. The shieldsystem can then be transported and processed in bulk, therebysubstantially eliminating the problems associated with prematureactuation of the shield system during bulk handling and processing andpermitting the use of high speed bowl feeders, etc. The shield systemsafter assembly may then be shipped in bulk to a pharmaceutical companyfor receipt of a syringe, such as a prefilled syringe containing a drug,vaccine or medicament.

The injection device, such as the prefilled syringe 120 shown in FIG. 5,is received in the open proximal end 30 of the body as shown in FIGS. 3and 5, wherein the sequence of installation of the syringe is shown inFIGS. 18A to 18C as now discussed. As the barrel 122 of the syringe isreceived in the open proximal end 30 of the shield assembly, as shown byarrow 98, the radial flange 126 at the proximal end of the barrel 122engages the proximal end of the ring shaped member 26, driving the ringshaped member distally and the V-shaped surfaces 76 then resilientlybias the legs 70 outwardly as shown in FIG. 18B, thereby releasing theinterlock between the body and the ring shaped locking member 26 asshown in FIG. 18C, wherein the opposed legs 70 are free to move distallyin the slots 40 in the body. As shown in FIG. 18C, however, the legscannot move proximally (i.e., toward the user) under the force of thecoil spring 28 because the proximal ends of the V-shaped portions arereceived beneath the opposed abutment surface 43 of the body, or theflange is interlocked with the body preventing proximal movement of thering shaped member. The syringe 120 is now ready for use and actuationof the shield system 20 as shown in FIG. 19A, wherein the radial portion60 of the first pair of fingers 56 is releasably retained on the opposedradial surface 42 of the body in the retracted position, which isreferred to hereinafter as the first retracted position.

The syringe 120 in the shield system 20 may then be used in the normalmanner after removal of the cap 136 shown in FIG. 5 and the needlecannula 128 is inserted into the patient, wherein the end user graspsthe finger flanges 44 of the body 22 and depresses the thumb pad 134 tomake an injection as shown by arrow 100 in FIG. 8. As the thumb pad 134is depressed to make the injection, it is moved toward the proximal endsof the legs 70 of the ring shaped member 26 as shown in FIGS. 9 and 19B.As set forth above, the legs 70 of the ring shaped member 26 are free tomove axially and distally in the slots 40 of the body 22 after releaseof the interlock between the ring shaped member 26 and the body 22.Continued depression of the thumb pad 134 by the user drives the thumbpad against the proximal ends of the legs 70 and the ring shaped member26 is thus moved distally as shown in FIG. 19B, wherein the rounded end88 of biasing surface 86 of the ring shaped member 26 first engages thecamming surface 66 and the biasing surface 86 then biases the secondpair of legs 58 toward the radial surfaces 42 of the body 22 or, in thedisclosed embodiment wherein the shield or needle cover 24 is receivedwithin the body 22, radially outwardly, such that the radial portions 64of the second pair of fingers 58 are coaxially aligned with the internalradial surfaces 42 of the body as shown in FIG. 19B. Continueddepression of the thumb pad 134 drives the ring shaped member 26distally, driving the outwardly inclined camming surfaces 84 against theopposed camming surfaces 62 of the first pair of fingers 56, resilientlybiasing the first pair of fingers 56 away from the body 22 or radiallyinwardly as shown in FIG. 19C, wherein the radial portions 60 arereleased from the opposed radial surfaces 42 of the body.

The needle cover or shield 24 then moves distally relative to syringe120 and body 22 under the force of the spring 28 as shown in FIG. 19D toa second retracted position, wherein the radial portions 64 of thesecond pair of fingers 58 are received on the opposed radial surfaces 42of the body and maintained in the second retracted position by thebiasing surfaces 86 of the ring shaped member, and the radial portion 60of the first pair of fingers 56 are spaced distally from the opposedradial surfaces 42 of the body as shown in FIG. 19D. As will then beunderstood from FIG. 19D, the shield or needle cover 24 is thusreleasably retained in the second retracted position as long as thethumb pad 134 of the plunger is maintained by the user.

When the thumb pad 134 is released by the user, the spring 28 drives thering shaped member 26 proximally as shown by arrow 102 in FIG. 19E,releasing the second pair of fingers 58, such that the second pair offingers resiliently return to their unbiased position which, in thedisclosed embodiment, results in radial inward movement of the secondpair of fingers 58, releasing the radial portions 64 of the second pairof fingers from the opposed radial surfaces 42 of the body. The needlecover or shield 24 is then driven distally by the spring 28 as shown byarrows 104 in FIG. 19E and the shield is thus extended from the secondretracted position shown in FIG. 19D to the extended position shown inFIG. 11, wherein the needle cover or shield 24 fully encloses the needlecannula 128 of the syringe as shown in FIG. 11. The needle cover 24 isthen locked in the extended position by the detents 48 adjacent thedistal end of the body 22 as shown in FIG. 20, wherein the radial rib 54of the needle cover 24 engages the inwardly inclined surface 106,resiliently biasing the detents 48 radially outwardly as shown inphantom in FIG. 20 to receive the radial rib 54 between the opposedabutment surfaces 108 and 110 of the detent 48 of the tubular barrel 46of the body 22 as shown in FIG. 20. Thus, the needle cover or shield 24cannot be retracted from the extended position, wherein the needlecannula 128 is enclosed by the needle cover as shown in FIG. 11 toexpose the needle cover following injection. The syringe and shieldsystem of this invention may thus be disposed of without potentialneedle sticks to the persons handling the syringe following injection.

As will now be understood, the user can thus select the timing of theactuation of the needle cover or shield. That is, the user can removethe needle cannula 128 from the patient prior to releasing the thumb pad134, such that the needle cover 24 does not contact the skin of thepatient, which is generally considered undesirable. Alternatively, theuser can release the thumb pad following injection while the needlecannula 128 remains in the patient, thereby releasing the needle coveror shield 24.

The embodiment of the shield system 220 illustrated in FIGS. 21 to 25may be substantially identical to the shield system 20 illustrated inFIGS. 1 to 20 except for the means of retaining the syringe in the body222. Except for the body 222, the components of the shield system 220may be identical to the shield system 20 described above and shown inFIGS. 1 to 20, including the needle cover or shield 24, the ring shapedmember 26 and the spring 28. Further, the operation of the shield system220 may be as described above. Thus, only the modified generally tubularbody 222 need be described herein in detail for a complete understandingof the shield system 220 shown in FIGS. 21 to 25.

Referring first to FIGS. 22 to 24, which illustrate the alternativeembodiment of the body 222, the generally tubular body 222 includes anopen proximal end 224, which receives the barrel 122 of the syringe 120,and an open distal end 226 as described above in regard to FIG. 5. Theopen proximal end 224 in this embodiment includes a generallyrectangular or square planar end wall 228 having truncated corners 230as described above. However, the shape of the proximal end of the body222 may be any convenient shape as described above. In this embodiment,the proximal end of the body 222 includes a plurality of generallyhook-shaped retainer elements which project proximally from the planarend wall 228 which retain the syringe 120 in the body 222 as nowdescribed.

The retainer elements include two pair of opposed spaced integral axialribs 232 which project proximally from the planar end wall 228 onopposed sides of the end wall each having an inclined inner surface 234terminating in an undercut 236 and an inclined outer surface 238terminating in an undercut 240. As described below, the spaced axialribs 232 receive the axially projecting legs 70 of the ring shapedelement 26 therebetween as shown in FIG. 21. The retainer elements 242on the opposed sides of the proximal end of the body each includeaxially projecting posts 244, which are integrally formed with the sidewalls, and a bridging portion 246 each having an inclined cammingsurface 248 and an undercut 250. As shown in FIGS. 23 and 24, theundercuts 236 and 248 are aligned axially and form proximal abutmentsurfaces with the opposed planar end wall 228. Thus, as described above,the syringe 120 is received in the open proximal end 224 of the body 222as shown in FIG. 5, wherein the flange 126 of the barrel 120 of thesyringe is received against the inwardly inclined camming surfaces 234and 248, resiliently biasing the retainer elements outwardly andreceiving the flange 126 of the syringe between the opposed abutmentsurfaces 236 and 250 of the retainer elements and the opposed planar endwall 228 of the body, retaining the syringe 120 in the body. Oneadvantage of this means of retaining the syringe in the body is that theflange 126 of the syringe is exposed, permitting inspection of theretainer elements following assembly to confirm that the syringe issecurely retained in the body following assembly.

As described above in the regard to the assembly of the shield system20, the needle cover or shield 24 (not shown in FIGS. 21 to 25) butdescribed above, is first received in the body, the spring 28 is thenreceived in the body and the ring shaped member or locking member 26 isthen received in the body and biased against the spring, wherein theproximally extending legs 70 are received between the ribs 232 and theV-shaped locking portions 76 interlock with the outer inclined surfaces238 and the undercut 240 as shown in FIG. 25. Thus, the assembly of theshield system 220 is substantially identical to the assembly of theshield system 20 described above, wherein the locking member 26 forms aninterlock with the proximal end of the body prior to receipt of thesyringe 120 limiting premature or inadvertent actuation of the shieldsystem.

This embodiment of the shield system 220 includes a further optionalsecurity feature reducing the likelihood of premature or inadvertentactuation of the shield system either during bulk shipping and handlingor by the user. This embodiment includes protective walls 252 on opposedsides of the ribs 232 which receive the projecting legs 70 of the ringshaped member 26 as shown in FIG. 21. The protective walls 252preferably have an axially length greater than the length of theprojecting legs 70, thereby reducing the likelihood of inadvertentcontact with the legs 70 during shipping and handling and by the user.As described above, the shield systems 20 and 220 are actuated bydepressing the thumb pad 134, which then engages the projecting legs 70of the ring shaped member 26, thereby moving the ring shaped member 26distally. Then upon release of the thumb pad 134, the needle cover 24shown in the prior figures is released and the spring 28 then drives theshield to the extended position shown in FIG. 11. The walls 252 arespaced from the ribs 232 sufficient to accommodate the receipt of thethumb pad 134 between the walls 252, but reduce the likelihood ofinadvertent engagement of the legs 70 either during bulk shipping andprocessing or by the user.

In the disclosed embodiment, the protective walls 252 are planar andintegrally formed with the finger grip 254 of the body. However, thewalls can be arcuate, for example, to partially surround the legs 70 andthe walls can also be formed integral with the proximal end of the bodydistally below the ribs 232. As described above, the shield ispreferably locked in the extended position following actuation and thedisclosed embodiment of the body 222 includes detents 256 which lock theshield in the extended position as described above. As set forth above,except for body 222, the remaining components of the shield system 220may otherwise be identical to the components of the shield system 20,including the needle cover or shield 24, the spring 28 and the ringshaped member 26.

Based upon the above description of the preferred embodiments of theshield system for a syringe of this invention, the assembly of theshield system and method of operation, the method of assembling a shieldsystem 20 or 220 on a syringe, such as the syringe 120 disclosed,comprises assembling the shield system 20 or 220 including the generallytubular body 22 or 222, the generally tubular needle cover or shield 24,the spring 28, and the locking member 26 which, in the disclosedembodiment is annular or ring shaped, wherein the shield 24 is in aretracted position and the locking member is interlocked with the body,preventing inadvertent or premature release of the shield from theretracted position to the extended position prior to receipt of thesyringe in the shield system 20 or 220. The method then includesinserting a syringe 120 in the shield system 20 or 220 through the openproximal end 30 or 224 of the body, thereby releasing the locking memberfrom the body and permitting actuation of the shield as described above.As also described above, the method of shielding a needle cannula of asyringe of this invention includes injecting a fluid through the needlecannula by driving the plunger 132 and stopper 130 through the barrel122 of the syringe, then releasing the plunger, thereby releasing theneedle cover or shield 24 from a retracted position to an extendedposition enclosing the needle cannula.

The components of the shield systems 20 and 220 of this invention may beformed of various materials. For example, the body 22, or 222, needlecover 24 and the ring shaped member 26 may be formed of plasticincluding clear plastic for visualization of the content of the syringe120. The body 22 or 222 and needle cover 24 are preferably formed of aresilient or semi-rigid plastic for operation of the interlock andrelease of the shield as described above. As will be understood by thoseskilled in this art, various modifications may be made to the shieldsystems 20 and 220 of this invention within the purview of the appendedclaims. For example, features of the shield system of this invention canbe incorporated in a shield system wherein the shield is telescopicallyreceived around the exterior surface of the body, particularly includingthe interlock feature. Further, the ring shaped member or locking member26 may include only one leg 70 or a plurality of legs greater than two.Although the locking member 26 is preferably ring shaped or annular asdisclosed, other shapes may also be utilized. Further, as describedabove, the fingers 56 and 58 of the needle cover 24 are preferablyopposed pairs of fingers as disclosed providing balanced support of theshield, the shield system of this invention may include only two fingersor a plurality of fingers greater than two. Finally, the internal radialsupport surfaces 42 in the body, which releasably support the needlecover in the body, may be spaced axially for each of the pairs offingers, wherein the radial portions would be adjusted axiallyaccordingly. Having described the preferred embodiments of the passivesafety shield system for syringes of this invention and method ofassembly and operation, the invention is now claimed as follows.

1. A method of shielding a needle cannula of a syringe with a shieldsystem, said syringe including a tubular barrel, a needle cannulaextending from a distal end of said barrel and a stopper within saidbarrel having a plunger rod extending through an open proximal end ofsaid barrel, and said shield system including a body receiving andretaining said syringe, a tubular shield surrounding at least a portionof said syringe barrel releasably retained to said body in a retractedposition, wherein said needle cannula is exposed and a spring urgingsaid shield toward an extended position, wherein said needle cannula isenclosed, said method comprising the following steps performed insequence: injecting a fluid through said needle cannula by driving saidplunger rod and said stopper through said barrel; and then releasingsaid plunger rod, thereby releasing said shield from said body and saidspring then driving said shield distally relative to said body to saidextended position enclosing said needle cannula.
 2. The method ofshielding a needle cannula of a syringe with a shield system as definedin claim 1, wherein said plunger rod includes a thumb pad at a proximalend, and said shield system including a locking member having at leastone leg extending towards said thumb pad, said method including drivingsaid thumb pad to engage said leg of said locking member, then releasingsaid thumb pad, thereby releasing said shield from said body.
 3. Themethod of shielding a needle cannula of a syringe with a shield systemas defined in claim 2, wherein said spring is operably biased betweensaid shield and said locking member and said locking member is moveableaxially relative to said body, said method including driving said thumbpad against said leg of said locking member, thereby driving saidlocking member axially and distally, then releasing said thumb pad, saidspring then driving said locking member proximally and releasing saidshield.
 4. The method of shielding a needle cannula of a syringe with ashield system as defined in claim 3, wherein said body includes a radialsurface and said shield includes a finger having a radial portionreleasably supported on said radial surface of said body in saidretracted position and said locking member including a camming surfaceopposite said finger, said method including driving said camming surfaceof said locking member against said finger of said shield, therebyreleasing said finger and said shield.
 5. The method of shielding aneedle cannula of a syringe with a shield system as defined in claim 4,wherein said shield includes at least two circumferentially spacedfingers each finger having a radial portion and said body includingopposed circumferentially spaced radial surfaces, one of said fingersbowed toward said one of said radial surfaces of said body releasablyretaining said shield in said retracted position, said method furtherincluding releasing said one of said fingers and substantiallysimultaneously biasing the other of said fingers to engage one of saidradial surfaces of said body by moving said locking member axially, thenreleasing said plunger rod, thereby releasing said other of said fingersand said spring then driving said shield from said retracted position tosaid extended position.
 6. The method of shielding a needle cannula of asyringe with a shield system as defined in claim 1, wherein said shieldsystem further includes a locking member, said method first includingassembling said shield system, including said body, shield, spring andlocking member with said shield in said retracted position and saidmethod including interlocking said locking member with said bodypreventing inadvertent release of said shield from said retractedposition to said extended position prior to receipt of said syringe insaid shield system, and then inserting said syringe in said shieldsystem through an open proximal end of said body, thereby releasing saidlocking member from said body and permitting actuation of said shieldsystem and extension of said shield from said retracted position to saidextended position.
 7. The method of shielding a needle cannula of asyringe with a shield system as defined in claim 6, wherein said barrelof said syringe includes a radial flange portion adjacent an openproximal end of said barrel and said method including inserting saidsyringe into said open proximal end of said body and said radial flangeof said barrel engaging and releasing said locking member from saidbody.
 8. The method of shielding a needle cannula of a syringe with ashield system as defined in claim 6, wherein said method includesinitially mechanically interlocking said body of said shield system withsaid locking member and said barrel of said syringe including a radialflange adjacent an open proximal end of said barrel, said method furtherincluding inserting said syringe in said open proximal end of said bodyand said radial flange of said barrel releasing said mechanicalinterlock.